KR20100121465A - Solid powder formulations for the preparation of resin-coated foils and their use in the manufacture of printed circuit boards - Google Patents

Abstract

The present invention relates to a solid thermosetting resin composition and a resin coated foil using the resin composition, a resin coated foil reinforced with glass fabric, and the use of the foil in the manufacture of a printed circuit board.

Description

Solid powder formulation for resin coated foil manufacture and use for printed circuit board manufacturing {SOLID POWDER FORMULATIONS FOR THE PREPARATION OF RESIN-COATED FOILS AND THEIR USE IN THE MANUFACTURE OF PRINTED CIRCUIT BOARDS}

FIELD OF THE INVENTION The present invention relates to solid powder formulations comprising a solid thermoplastic resin composition, optionally reinforced, resin coated foils made from such formulations, and the use thereof in the manufacture of printed circuit boards.

In order to manufacture printed circuit boards (PCBs), thermosetting epoxy resin formulations are widely used. Thermosetting epoxy resin formulations are still the industry standard for most electronic applications because of their reasonable price and good overall technical properties (Martin W. Jawitz (Ed.), Printed circuit board materials handbook, McGraw Hill, New York, 1997, chapter 6). Important properties that make the epoxy so versatile are, for example, good thermal stability, good copper peel strength or low water absorption. In order to ensure the flame retardance required for the finished electronic product, the epoxy resin itself is generally formulated to be flame retardant. Such formulations can be made, for example, by using brominated epoxy resins. However, due to environmental problems and requests from original equipment manufacturers (OEMs), the use of such resins is increasingly limited. Accordingly, other flame retardants based on phosphorus compounds or metal hydroxides (eg Al or Mg hydroxides) are used.

To improve mechanical properties, prepreg and laminates are often manufactured by treating epoxy resin and reinforcing materials in combination (Martin W. Jawitz (Ed.), Printed circuit board materials handbook, McGraw Hill, New York, 1997, chapter 9). The most used tempered material at present is glass fabric. For example, prepregs are typically prepared by impregnating a glass fabric in a so-called treatment agent in which the fabric is immersed in a solvent-based solution of an epoxy resin formulation and then slowly evaporating the solvent and simultaneously b-staging the resin. Due to the low viscosity of the solution, good wetting of the glass fabric is easily achieved.

In essence, solvent-based processes have some serious drawbacks. The solvent itself is not part of the finished product. That is, the solvent only acts as a carrier medium for the solute (eg epoxy resin formulation). Such solutions generally have about 50% solids. This means that after the solvent has been used for that purpose, the solvent must be evaporated through a process that requires a large amount of energy, which must be disposed of mainly by incineration, ie about 50% of the raw material is used up as waste. do. This significantly increases investment costs and increases the operating costs of the plant in question. Health, environmental and safety issues and VOC regulations are also important considerations from another perspective. In addition, the coating lines of the devices that need to handle solvent-loaded waste air and the detectors that must prevent explosive atmospheres become complicated and expensive. The process, which takes some time to re-level the surface again after releasing the solvent, is inherently slower and less efficient than simply melting and leveling the powder matrix. Moreover, when a powder coating is used, the solvent-free state of the intermediate and the final product is ensured even when a rapid curing system is used. In view of this, high yields and relatively small coating lines can be achieved. On the other hand, raw materials used in the printed circuit board industry must meet stringent requirements. In particular, ultra-thin prepregs or resin coated foils for making high density interconnect (HDI) layers must meet a much wider range of OEM requirements than would be required from conventional powder coating applications. The excellent solder impact resistance necessary to pass through multiple lead-free solder reflow cycles requires excellent thermal stiffness. Low absorbency is required to meet the requirements of the Koint Electron Device Engineering Council (JEDEC) (see references to JEDEC requirements, numerous lead-free solder impact tests, and CAF immunity). The low melt viscosity allows for complete impregnation of the fabric glass fibers which is essential for the material to be resistant to conductive anodic filament growth (CAF resistance). All these properties must be maintained in the presence of halogen-free flame retardants required to reach sufficiently low UL-V0 burn times.

Most thermosetting resin compositions used for impregnation of glass fabrics and coating of substrates used in the PCB industry are diluted in the majority of the raw materials applied as well as organic solvents. All available halogen free flame retardants are liquid phosphorus containing components or solid additives that are not diluted or are unlikely to react into the thermosetting epoxy resin matrix. On the other hand, although metal hydroxides may be used, such fillers require an unacceptably high loading. In general, these fillers all degrade mechanically and other properties to a significant extent. In addition, high filler loadings greatly increase the melt viscosity, thereby lowering the wetting ability of the fibers. Therefore, it would be desirable to provide an epoxy resin formulation based primarily on 100% solids having the ability to impregnate and wet the glass fabric. Such a solid resin formulation can be prepared as a powder and used as it is.

The solid resin formulation must meet several boundary conditions. The Tg of the composition in the uncured state (step A) must be high enough to carry out the various processing steps (extrusion, grinding, fractionation, sifting) necessary to prepare the powder. If the Tg is too low, deadlocks may occur. At the same time, the melt viscosity of the composition at high temperature should be low enough so that the glass fabric can be impregnated properly with the resin. In addition, excellent heat resistance, UL-V0 combustion performance without halogenated components, low water absorption, and good copper adhesion are critical parameters to meet typical requirements for base materials used in PCB applications.

WO 2004/085550 A2 relates to powder coatings, aqueous dispersions based on said powder coatings, methods for their preparation and methods for preparing coating layers on substrates, in particular for producing multilayer structures. The method does not require the use of organic solvents at all.

It is an object of the present invention to provide a powder coating composition which is capable of rapid curing at low melt viscosity but still at high powder Tg (greater than 50 ° C.). The composition of the present invention should be useful for making flame retardant resin coated foils, wherein the flame retardant should not adversely affect the curing mechanism. It is also an object of the present invention to provide compositions which exhibit high copper peel strength, improved shelf life and good processing properties such as high throughput in the grinding process. The composition should be able to successfully impregnate the glass fabric without forming voids, wet defects, bubbles, etc. in subsequent lamination steps.

According to the invention, the above object is achieved by a powder formulation comprising a thermosetting resin composition containing the following components (A) to (D):

(A) an epoxy resin which is solid at 20 ° C.,

(B) a phenolic curing agent having an average functional group greater than 3, preferably greater than 5, more preferably greater than 7, most preferably greater than or equal to 9 and solid at 20 ° C,

(C) phosphorus modified epoxy resin which is solid at 20 ° C, and

(D) latent catalyst.

Detailed description of the invention

The component (A) is preferably a chemically modified epoxy resin having an epoxy equivalent (EEW) in the range of 150 to 1800 g / eq.

The term "epoxy equivalent" (EEW) is defined as the weight of a resin in grams containing one gram equivalent of epoxy. If the chain of the resin is assumed to be linear with no branched side chains and the epoxy group is at the end of each end, the epoxide equivalent is 1/2 of the average molecular weight of the diepoxy resin and 1/3 of the average molecular weight of the triepoxy. . In the art, the term "epoxy value" is also used to denote the fraction of epoxy groups contained in 100 g of resin. The two terms are used interchangeably. Dividing the epoxy number by 100 gives the epoxide equivalent weight. The actual method of determining the epoxide equivalent weight is based on adding hydrogen halide to the epoxy group. The difference between the amount of acid added and the amount not consumed, determined by titration with a standard base, is a measure of the epoxy content. In practice, hydrogen chloride, hydrogen bromide or hydrogen iodide is used.

Examples of the chemically modified epoxy resins include isocyanate modified epoxy resins, butadiene-acrylonitrile rubber modified epoxy resins, polyfunctional epoxy-phenol novolak resins, and bisphenol-A or cycloaliphatic epoxy resins.

Suitable solid curing agents (B) for use in the present invention are selected from the group consisting of phenol novolak resins, cresol novolak resins and bisphenol A novolak resins, which do not have any epoxy groups as the curing agents disclosed in WO 2004/085550 A2. .

According to a preferred embodiment of the present invention, the solid curing agent (B) is a phenol novolak resin having an average number of functional groups of 9 or more, wherein the average number of functional groups is the average number of functional groups (-OH) per molecule. Examples of such solid curing agents include TD2131 (commercially available from Dainippon Ink & Chemicals Inc.) and PF 0790 K04 (commercially available from Hexion).

Component (C) is, for example, DOPO (di-hydro-9-oxa-10-phosphaphenanthrene-10-oxide) modified multifunctional epoxy phenol or cresol novolak resin and DOPO-HQ (2- (6- Oxo-6H-6,5-dibenzo [c, e] [1,2] oxaphosphin-6-yl) benzene-1,4-diol) modified difunctional epoxy resin) Phosphorus modified epoxy resin. Stuktol VP 3752 (available from Schill + Seilacher) and EXA 9726 (available from Dainippon Ink and Chemicals, Inc.). Exa 9726 basically corresponds to Exa 9710, a solution of Exa 9726 in an organic solvent (MEK, acetone).

Another suitable solid phosphorus modified epoxy resin for use in the present invention is disclosed in US Patent Application Publication No. US 2006/0223921 A1. This patent publication discloses a prepolymer for a flame retardant polymer, which is prepared by reacting, for example, an epoxy resin with at least one phosphinic acid derivative represented by the following general formula (1):

(Formula 1)

(R ¹ O) (R ² ) P (O) -R ³

Wherein R ¹ and R ² independently of each other represent an optionally substituted alkyl, aryl, arylalkyl, alkylaryl or alkylarylalkyl group having 1 to 20 carbon atoms;

R ³ represents a hydrogen atom or an optionally substituted alkyl, aryl, arylalkyl, alkylaryl or alkylarylalkyl group having 1 to 20 carbon atoms.

Another phosphorus modified epoxy resin suitable for use in the present invention is disclosed in Japanese Patent Application Publication No. JP 2000080251.

According to a preferred embodiment of the present invention, the solid phosphorus modified epoxy resin is a bifunctional epoxy resin having an EEW of less than 500 g / eq and a phosphorus content of more than 2% by weight.

Component (D) is a latent catalyst. The latent catalyst is chemically protected at ambient temperature, and the catalytically active component is produced at high temperatures above 120 ° C., examples of which are available from Dihard ^® UR 300 and Dihard UR 500 (Degussa). ).

The latent catalyst (D) is a substituted urea catalyst or ureon catalyst. Such substituted urea catalysts are represented by the following general chemical formula:

 Wherein R 1 represents a substituted or unsubstituted phenyl group and R 2 and R 3 may be the same or different and are selected from straight or branched chain alkyl groups having 1 to 6 carbon atoms.

When such a substituted urea catalyst chloride quaternary general formula ^{[R 1 R 2 NC (OR} 3) = NR 4 R 5] + X - is selected from: (wherein, R ¹ to R ⁵ is a hydrogen atom or an organic residue, X ^- is formed with a catalyst represented by the neurons is an acid anion).

Examples of suitable uron type catalysts suitable for use in the present invention include URAcc43 (available from Degussa).

The thermosetting resin composition may optionally further include an inorganic filler (E). Such inorganic fillers include SiO ₂ , Al ₂ O ₃ , AlOOH, kaolin and talc.

The average particle size of the inorganic filler is preferably less than 5 micrometers.

The composition of the powder formulation may vary depending on the physical properties required, but generally comprises components (A) to (D) and optionally component (E) in the amounts described below:

(i) 25-50% by weight of component (A), preferably 35-45% by weight,

(ii) 15-25% by weight of component (B),

(iii) 15-25% by weight of component (C),

(iv) 0.05-1% by weight of component (D),

(v) 0-40% by weight of component (E), preferably 20-30% by weight.

For example, preferred compositions include 35-45% of epoxy resins selected from: XAC 4151 (available from Asahi Kasei), AER 4151 (available from Asahi Kasei), EPPN 502H (Nippon Kayaku) (Available from Nippon Kayaku), Hypox RK84L (available from CVC) and mixtures thereof. Preferred embodiments of component (A) consist of all four of said epoxy resins.

A suitable curing agent (B) for use with such epoxy mixtures is PF 0790 K04 (commercially available from hexion).

According to a preferred embodiment of the present invention, Exa 9726 (commercially available from Dainippon Ink and Chemicals, Inc.) is used as the phosphorus modified epoxy resin.

It is preferred to use URAcc43 (commercially available from Degussa) together with the mixture as a latent catalyst.

Particularly preferred powder formulations are XAC 4151 (available from Asahi Kasei), AER 4151 (available from Asahi Kasei), EPPN 502H (available from Nippon Kayaku), Hypox RK84L (available from CVC), PF 0790 K04 ( Commercially available from Hexion), Exa 9726 (available from Dainippon Ink and Chemicals, Inc.) and URAcc 43 (available from Degussa) in amounts of (i) to (iv) as previously described do.

The composition according to the invention is characterized by having a high potential and a high glass transition temperature after curing.

In the present invention, the potential is defined as follows:

Potential [° K] = Exothermic Peak Temperature [° C]-Exothermic Onset Temperature [° C] (measured by differential scanning calorimetry (DSC)).

Thus, the low latent value (range from initiation temperature to peak temperature) indicates that the reaction heat peak is narrower and more latent hardening mechanism, especially when the initiation temperature is higher than 150 ° C and the peak temperature is lower than 180 ° C. it means. A wider enthalpy peak means that the shelf life is reduced and does not cure quickly.

High glass transition temperatures (Tg) after curing are preferred in this application because many physical properties deteriorate near the glass transition temperature. For example, near the glass transition temperature, the stiffness decreases and the thermal expansion rate increases.

As described below, the composition according to the present invention achieves high potential and high Tg after curing by using the catalyst (D) and the curing agent (B) in combination. In other words, the combination of a curing agent, in particular a curing agent with an average number of functional groups of more than 3, preferably more than 5, more preferably more than 7, most preferably at least 9, and a latent catalyst, specifically a substituted urea or uron type catalyst, It has significantly better performance than the thermosetting epoxy resin compositions of the prior art.

The composition according to the present invention preferably has a potential of less than 20 K, which is measured in the range from the initiation temperature to the peak temperature. The onset temperature is in the range of 140-160 ° C., and the peak temperature is preferably less than 180 ° C.

After curing, the compositions of the present invention preferably have a Tg in the range of 150-160 ° C.

Another important feature of the compositions according to the invention is that the shelf life is improved and that they cure quickly. Both of these features are important in the handling and processing of the resin compositions used to make resin coated foils. In the composition according to the invention, no significant curing occurs below 120 ° C., and rapid curing occurs at high temperatures above 150 ° C. At a temperature of 160 ° C., the formulation can be fully cured within 20 minutes, and at 170 ° C., only 15 minutes of firing time is sufficient to achieve complete curing.

The shelf life of the composition according to the invention is evidenced by the fact that its reaction enthalpy loss is less than 15%. No significant changes occur with regard to melt viscosity and flow characteristics. When the composition according to the invention was stored at a temperature below 6 ° C., no change in the heat of reaction was observed.

In view of improved shelf life, the powder formulations according to the invention can be stored for over 6 months.

In addition, the compositions according to the invention exhibit improved flame retardancy with respect to the amount of flame retardant and the effect of the flame retardant on the curing mechanism. Thus, the flame retardant has a similar chemical structure to the epoxy resin used as component (A) in the composition according to the invention, except that it comprises phosphorus as an additional component. Therefore, the flame retardant is incorporated into the skeletal structure obtained by curing the thermosetting resin composition, and this incorporation may result in a lower concentration of the flame retardant required to achieve the VO grade as compared to the use of conventional flame retardants known in the art. In addition, in terms of this structural similarity, the flame retardant does not adversely affect the curing mechanism for thermosetting the composition, since the flame retardant becomes part of the crosslinked product.

Particularly preferred solid phosphorus modified epoxy resins for use in the present invention are 2- (6-oxo-6H-6,5-dibenzo [c, e] [1,2] oxaphosphin-6-yl) benzene-1 , 4-diol) and a polyaddition product of (phenol / formaldehyde polycondensation product and etherification product of 1-chloro-2,3-epoxypropane). The structure of such a DOPO modified multifunctional epoxy phenol novolak resin is as shown below:

Another solid phosphorus modified epoxy resin particularly preferred for use in the present invention is an HCA-HQ modified bifunctional bisphenol A epoxy resin as shown below:

Methods for producing such epoxy resins are disclosed in Japanese Patent Application Publication No. JP 2000080251 and US Patent Application Publication No. US 2006/0223921 A1.

The solid phosphorus modified epoxy resin significantly reduces the total burn time of the sample tested. At the same time, the sample exhibits superior copper peel strength compared to a sample comprising conventional phosphorus flame retardant.

In short, the composition according to the present invention has improved physical properties suitable for use in the manufacture of resin coated foils that can be used in the manufacture of printed circuit boards. Specifically, the powder formulation comprising the thermosetting resin composition as described above has the following physical properties:

(i) a glass transition temperature above 50 ° C. in unconverted A-stage, measured by DSC according to IPM 650 2.4.25 C,

(ii) a melt viscosity of less than 20 Pas at 140 ° C., measured using a cone plate shape with an angle of 2 ° and a rotational speed of 5 rpm,

(iii) a glass transition temperature above 150 ° C. after curing at 190 ° C. for 20 minutes, as measured by DSC according to IPM 650 2.4.25 C,

(iv) a decomposition temperature of greater than 390 ° C. under 1 wt% loss, as measured by thermogravimetric analysis (TGA), and

(v) Dielectric constant (Dk) less than 3.4 and extinction coefficient (Df) less than 0.018, as measured by ASTM D 150-98 (2004) and measured at 1 GHz.

Since the above-mentioned thermogravimetric analysis (TGA) is well known in the art that can be used to measure the weight change of a sample with temperature, TGA is a tool that can analyze the pyrolysis pattern or profile of a material.

In addition, the present invention can be obtained by coating a substrate with a powder formulation as described above to obtain a coated substrate, and heat-fixing the powder formulation to the substrate at a high temperature such as a temperature of 150 ℃ or more to produce a resin coated foil. It provides a resin coated foil.

Suitable substrates for use in such coating methods are selected from metal foils, such as copper, aluminum or nickel foils, as well as polymer foils that withstand high temperature exposure to melt the thermosetting resin composition at desired levels.

The resin coated foil preferably comprises a reinforcing agent, preferably a reinforcing agent used to prepare the prepreg or laminate. Such reinforcing agents include cloth and glass cloth.

Thus, the present invention provides a resin coated foil reinforced with clads having metals such as, for example, E-glass fabrics and electrodeposited copper.

This reinforced resin coated foil withstands the peel test for more than 30 minutes when tested by the peel test according to IPC ™ 650 2.4.24.1. In addition, the reinforced resin coated foil exhibited a copper peel strength of greater than 17 N / cm under 35 micron copper thickness in a test by IPC ™ 650 2.4.8 C.

After removing the copper clad, the laminate structure as described above withstands solder immersion test at 288 ° C. for 20 seconds after boiling in a high pressure cooking vessel for 30 minutes under 2.6 bar (corresponding to 140 ° C.). Low delamination or surface foaming is observed in the test according to 650 2.6.16. The 40 micrometer thick film exhibits less than 1% absorbency in tests by IPC ™ 650 2.6.2 C.

When tested by the vertical UL-combustion test, the glass fabric reinforcement film compresses to an additional thickness of 240 micrometers (corresponding to six plies) on a 200 micrometer thick FR4 core in the absence of halogenated components, or 160 as the laminate itself. Compress up to a micrometer thickness (corresponding to 4 layers) or obtain a V0 rating.

The formulation of the thermosetting resin composition of the present invention can be carried out by an extruder, wherein the slow incorporation of the catalyst C is an important parameter for maintaining this potential. Cooling with a cold belt and a cooling roller lowers the temperature of the melt, ultimately allowing the melt to break up into flakes.

The powder is prepared by the grinding process from the flakes, for example using an impact mill or an air jet mill. If necessary for the subsequent coating process, a classifier can be used to remove particulates from the powder. In this way, the average particle size can be adjusted to a predetermined value.

The powder may be applied onto a substrate, such as a metal foil as described above, to be thermally fixed on the substrate at high temperature.

1 shows a DSC scan of the powder formulation of the present invention and the formulation of the comparative example.
2 shows the cure rate, expressed as% conversion of the composition according to the invention at various temperatures.

Hereinafter, the present invention will be described in more detail with reference to Examples. In the examples described below, most of the test methods performed are related to IPC ™ 650 (Electronic Circuit Connection Association). The manual establishes a unified method for testing electronic and electrical components, including basic environmental, physical and electrical tests. These tests were developed to support IPC standards and requirements (IPC ™ 650 (Electronic Circuit Connection Association) 2215 Sanders Road, Northbrook, Illinois 60062-6135).

More specifically, the following parameters were tested as described below:

(a) Glass transition temperature (Tg) after curing was measured according to IPC ™ 650 2.4.25 C.

(b) Gelation time was measured according to IPC ™ 650 2.3.18 A.

(c) Peel time (TMA method) was measured according to IPC ™ 650 2.4.24.1.

(d) The viscosity was measured using a conical plate shape having an angle of 2 ° and a rotational speed of 5 rpm. The temperature was set at 140 ° C. (± 0.5K).

(e) HPCT was measured according to test method IPC ™ 650 2.6.16.

(f) Peel strength was measured according to IPC ™ 650 2.4.9.

(g) Total burn time (per sample) was measured according to IPC ™ 650 UL.

(h) Absorbency was measured according to IPC ™ 650 2.6.2.1.

Example 1

A thermosetting resin composition was prepared using the following ingredients:

Curing Agent A: Phenolic Novolak Resin (Average B) with an Average Number of Functional Groups ≥ 9

Curing Agent B: Phenol Novolac Resin with Average Functional Group <3

Catalyst 1: imidazole derivatives such as 2-phenylimidazole curzol 2-PZ, sold by Shikoku Co., Ltd.

Catalyst 2: Substituted Urea Catalyst (Component D)

After the formulations shown in Table 1 were mixed at high temperature, they were examined by differential scanning calorimetry (DSC) at temperatures ranging from -30 ° C to 300 ° C to determine reaction enthalpy and glass transition temperature after curing. A typical DSC scan is shown in FIG.

(Table 1)

* Tg after curing measured by DSC → IPC TM 650 2.4.25 C

** Gelation time → IPC TM 650 2.3.18 A

*** Peel time (TMA method) → IPC TM 650 2.4.24.1

In this investigation, the isocyanate-modified epoxy resin formed a main chain. The amount of curing agent was set at stoichiometric ratio. The catalyst content was 0.8% by weight in all formulations.

The values in Table 1 above demonstrate that even the right combination of catalyst and curing agent achieves both the desired low potential and high post Tg curing. The combination of a hardener having a high functional group and a uron type catalyst (Formulation ST00034-2) is remarkably superior to other comparative examples (Formulations ST00034-1, ST00034-3, and ST00034-4).

Example 2

The shelf life and curability of the following formulations were tested as follows:

The reaction enthalpy loss was used to confirm the shelf life of the fully formulated powder. The reaction enthalpy immediately after preparation was measured and used as a reference. The powders were then stored at ambient temperature of <23 ° C. and tested again after 3 and 6 months. Curing status was tested via DSC. Samples were exposed to various temperatures and times inside the DSC measurement cell. After exposure, the residual reaction enthalpy was detected and used as the degree of conversion.

As shown in FIG. 2, no significant curing occurs below 120 ° C., but rather rapid curing at high temperatures above 150 ° C. At a temperature of 160 ° C. the formulation can be fully cured within 20 minutes, and at 170 ° C., only 15 minutes of firing time is sufficient to achieve complete curing.

To demonstrate the shelf life of all of the several formulations (different epoxy resin combinations) cured using the combination of the phenolic curing agent and protected catalyst of the present invention, the reaction enthalpy loss is shown in Table 2 below. In general, a decrease in reaction enthalpy of less than 15% is allowed, which does not cause significant changes in melt viscosity and flow properties. When the formulation was stored at temperatures below 6 ° C., no change in heat of reaction was observed.

(Table 2)

* Powder stored for more than 6 months at ambient temperature

** Powders stored for more than 3 months at ambient temperature

Formulation Details

ST00036: contains the above isocyanate modified epoxy resin, phenol novolak curing agent (B), inorganic filler (E) and substituted urea catalyst (D)

Silbond is a SiO ₂ filler available from Quarzwerke.

** EPON 1031 is a solid multifunctional epichlorohydrin / tetraphenylol ethane epoxy resin available from Hexion (partially UV-blocked)

Example 3

Formulation ST00036 described in Example 2 above was used as a reference material and the following phosphorus sources were added in the proportions necessary for the total phosphorus content to be 1% by weight.

The phosphorus content, melting point and chemical structure of the flame retardants used are shown in Table 3 below.

The list below contains only phosphorus sources which are inherently likely to be obtained, for example, in powder formulations having a melting point above 50 ° C.

(Table 3)

All of the phosphorus sources tested were efficient and significantly reduced the total burn time. When using component C, the best overall performance was obtained. Free DOPO containing formulations showed very poor performance with respect to T288 resistance and copper peel strength. The DOPO derivative HCA-HQ is better, but residual (unconverted) particles were observed. It is believed that this is mainly due to the high melting point of the component. In addition, component XZ 92588 significantly reduced the copper peel strength. Reference may be made to the results in Table 4 below. The standard material ST00036 does not contain any flame retardants.

(Table 4)

* Samples compressed with glass fabric reinforced resin coated copper foil (R-RCF)

In short, the present invention provides a powder coating composition comprising an epoxy resin, a solid curing agent, a phosphorus containing bifunctional flame retardant having a structure similar to the epoxy resin, a latent catalyst, in particular a urea catalyst and optionally an inorganic filler. Such a combination of a curing agent and a catalyst allows for rapid curing under low Tg (greater than 50 ° C.) of a low melt viscosity. The phosphorus-containing flame retardant becomes part of the resin main chain. The flame retardant may be used in a small amount compared to conventionally used flame retardants, and does not adversely affect the curing mechanism.

The compositions according to the invention exhibit good processing properties such as high copper peel strength, improved shelf life, and high throughput in the grinding process.

Claims (24)

(A) an epoxy resin which is solid at 20 ° C.,
(B) a phenolic curing agent that is solid at 20 ° C. with an average number of functional groups greater than 3,
(C) phosphorus modified epoxy resin which is solid at 20 ° C, and
(D) latent catalyst
Powder formulation containing the thermosetting resin composition containing these. The powder formulation of claim 1, wherein the epoxy resin (A) is a chemically modified epoxy resin having an epoxy equivalent in the range of 150 to 1800 g / eq. The powder formulation according to claim 1, wherein the solid phenolic curing agent (B) is a phenol novolak resin having an average number of functional groups of 9 or more. The powder formulation of claim 1, wherein the solid phosphorus modified epoxy resin (C) is a difunctional epoxy resin having an epoxy equivalent of less than 500 g / eq and a phosphorus content of more than 2 wt%. The powder formulation of claim 1, wherein the latent catalyst (D) is a substituted urea or uron type catalyst. The powder formulation of claim 1 further comprising an inorganic filler (E). 7. Powder formulation according to claim 6, wherein the average particle size of said inorganic filler (E) is less than 5 micrometers. The method according to any one of claims 1 to 7,
(i) 25-50% by weight of component (A),
(ii) 15-25% by weight of component (B),
(iii) 15-25% by weight of component (C),
(iv) 0.05-1% by weight of component (D),
(v) component (E) 0-40% by weight
Powder formulation containing as a main component. The method according to any one of claims 1 to 7,
(i) 35-45 wt% of component (A),
(ii) 15-25% by weight of component (B),
(iii) 15-25% by weight of component (C),
(iv) 0.05-1% by weight of component (D),
(v) 20-30% by weight of component (E)
Powder formulation containing as a main component. The epoxy resin (A) according to claim 1 or 2, wherein the epoxy resin (A) isocyanate-modified epoxy resin, butadiene-acrylonitrile rubber-modified epoxy resin, polyfunctional epoxy-phenol novolak resin and bisphenol-A or cycloaliphatic epoxy Powder formulation selected from the group consisting of resins. The method according to claim 1 or 3,
The powder formulation of the solid phenolic curing agent (B) is selected from the group consisting of phenol novolak resin, cresol novolak resin and bisphenol A novolak resin. 5. The method of claim 1 or 4, wherein the solid phosphorus modified epoxy resin is 2- (6-oxo-6H-6,5-dibenzo [c, e] [1,2] oxaphosphin-6-yl. ) Is a polyaddition product of benzene-1,4-diol) with (phenol / formaldehyde polycondensation product and etherification product of 1-chloro-2,3-epoxypropane). The powder formulation according to claim 1 or 5, wherein the latent catalyst is selected from the group of compounds represented by the following general formula (1):
(Formula 1)

(In Formula 1, R1 represents a substituted or unsubstituted phenyl group, and R2 and R3 may be the same or different and are selected from straight or branched chain alkyl groups having 1 to 6 carbon atoms.) 8. Powder formulation according to any one of claims 1, 6 and 7, wherein said filler is selected from the group consisting of SiO ₂ , Al ₂ O ₃ , AlOOH, kaolin and talc. The method according to any one of claims 1 to 14,
(i) a glass transition temperature above 50 ° C. in unconverted A-stage, as measured by DSC according to IPM 650 2.4.25 C,
(ii) a melt viscosity of less than 20 Pas at 140 ° C., measured using a cone plate shape with an angle of 2 ° and a rotational speed of 5 rpm,
(iii) a glass transition temperature above 150 ° C. after curing at 190 ° C. for 20 minutes as measured by DSC in accordance with IPM 650 2.4.25 C,
(iv) a decomposition temperature of greater than 390 ° C. under 1 wt% loss, as measured by thermogravimetric analysis (TGA), and
(v) Dielectric constant (Dk) of less than 3.4 and extinction coefficient (Df) of less than 0.018, as measured by ASTM D 150-98 (2004) and measured at 1 GHz
Powder formulation having a. A coated substrate is prepared by coating the substrate with the powder formulation according to any one of claims 1 to 15, and obtained by producing a resin coated foil by thermally fixing the powder formulation to the substrate at a high temperature of 150 ° C or higher. Resin coated foil. The resin coated foil of claim 16 comprising a reinforcing agent for forming the prepreg or laminate. 18. The resin coated foil of claim 17 wherein said reinforcing agent is selected from the group consisting of fabric cloth and glass cloth. 19. The resin coated foil of claim 18, wherein the clad reinforced foil has an E-glass fabric and electrodeposited copper. 20. The resin coated foil of claim 19 having a copper peel strength of greater than 17 N / cm under 35 micron copper thickness and withstanding peeling at 300 ° C. for more than 30 minutes. The resin-coated foil of claim 20 which withstands the solder dip test at 288 ° C. for 20 seconds after removing the copper clad and boiling in an autoclave for 30 minutes. 22. The method of claim 21, which does not contain halogenated compounds and is compressed to an additional thickness of 240 micrometers equal to six ply on a 200 micrometer thick FR4 core, or 160 micrometers each corresponding to four ply as the laminate itself. Resin coated foil that compresses to thickness or passes the vertical UL-burn test to a V0 rating. (i) mixing components (A) to (D) and optionally component (E);
(ii) melt extruding the mixture obtained in step (i); And
(iii) pulverizing and sifting the extruded mixture, wherein the powder preparation according to any one of claims 1 to 15 is prepared. 23. Use of a resin coated foil according to any one of claims 16 to 22 for the manufacture of a printed circuit board.

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